1. Field of the Invention
The present invention relates generally to networks and, more particularly, to quality of service, contention-based media access control for mobile ad hoc networks.
2. Description of Related Art
The use of ad hoc wireless networks has increased in recent years. An ad hoc wireless network typically includes several wireless, usually mobile, nodes. In such a network, each of the nodes may be equipped with a radio that allows the node to communicate with other nodes to form a network. The nodes typically include a media access controller (MAC) that determines when data can be sent via radio waves to another node. The MAC algorithm that determines the appropriate times to send data is often very complex.
MAC algorithms generally fall into two broad categories: centralized and decentralized. In a mobile ad hoc environment, the infrastructure associated with the network is not guaranteed. Therefore, decentralized algorithms are typically used. Within the decentralized category, there are two general types of MAC algorithms: schedule-based and contention-based.
Schedule-based algorithms are time-oriented techniques in which each node knows when it is time to transmit. This requires time synchronization and decentralized coordination throughout the network to ensure that time slot information is consistent across the network. This is cumbersome and requires considerable overhead at the MAC layer in order to operate properly. Such a technique is also sub-optimal for bursty data.
Contention-based algorithms are channel-oriented techniques in which each node senses the state of the channel. In this technique, a node waits for the channel to be sensed as clear and then transmits its data. This technique may be optimal for bursty data, but is sub-optimal for quality of service (QoS) based data.
Another problem in conventional ad hoc networks is that nodes typically have equal access to the shared communication medium. This causes problems when a node wishes to transmit high priority data and is unable to seize the shared communication medium.
Therefore, a need exists for systems and methods that enable nodes to perform QoS, contention-based media access control in a wireless network that efficiently supports both bursty and non-bursty traffic. A need also exists for systems and methods that enable nodes to gain access to a shared communication medium based on data priority.